Jan von Delft

The Kondo exciton: non-equilibrium dynamics after a quantum quench in the Anderson impurity model

Location: Dahlem Center roomTime: Tuesday 03.11.2009, 10h s.t.

A single confined spin interacting with a solid-state environment has emerged as one of the fundamental paradigms of mesoscopic physics. In contrast to standard quantum optical systems, decoherence that stems from these interactions cannot be treated using the Born-Markov approximation at low temperatures. Here we study the non-equilibrium dynamics following a quantum quench of a single-spin in a semiconductor quantum dot adjacent to a Fermionic reservoir and show how the dynamics can be revealed in detail in an optical absorption experiment. We show that the highly asymmetrical optical absorption lineshape of the resulting Kondo exciton consists of three distinct frequency domains, corresponding to short, intermediate and long times after the initial excitation, which are in turn described by the three fixed points of the single-impurity Anderson Hamiltonian. In particular, the zero temperature power-law singularity dominating the lineshape is linked to dynamically generated Kondo correlations in the photo-excited state.